1. Field of the Invention
The present invention relates to an accumulator fuel injection system with a common rail which is applied to a diesel engine, high pressure fuel being accumulated in the common rail and supplied at a constant interval to the injection nozzle of each cylinder from high pressure fuel outlet ports disposed at a constant spacing in the common rail.
2. Description of the Related Art
Accumulator fuel injection systems in which high pressure fuel accumulated in a common rail is supplied to the injection nozzle of each cylinder at determined injection timing are in heavy usage in recent years in diesel engines.
In an accumulator fuel injection system like this, pressure pulsation occurs in the common rail induced by the opening and closing of the injection nozzles. The outlet ports connecting to injection pipes are arranged with the same pitch in the common rail and the fuel injection interval is also the same for each cylinder, so a standing wave resides in the common rail, and this standing wave may affect the next injection.
In Japanese Laid-Open Patent Application No. 11-159372 is disclosed a means to eliminate the influence of the pulsation of fuel pressure in the common rail.
According to the disclosure, by use of an electronic control device, a difference of injection pressure to be corrected is determined based on the set value of fuel injection quantity, injection pressure of fuel is determined according to the pressure to be corrected with the injection valve opening period being reflected for the correction, and injection valve opening periods are controlled taking into consideration the reflection of fuel pressure so that the quantity of fuel optimal for the operating condition of the engine and for pulsating condition of fuel pressure is injected even when fuel pressure pulsation occurs in the fuel injection line and the reflection wave of fuel synchronizes with the injection of the next cylinder.
However, there is a problem in the art disclosed in the Japanese Laid-Open Patent Application No. 11-159372 in that, as a difference of injection pressure to be corrected is determined based on the set value of fuel injection quantity and the opening period of the injection valve is controlled by an electronic control device based on the corrected injection pressure taking the reflection wave of the fuel pressure into consideration, the program for calculation and control is inevitably complicated and the cost of the system is increased for providing the electronic control device.